It is sometimes required in certain optical instruments and devices to move, rotate, or vary the position of optical elements, such as filters, mirrors, attenuators, and the like. The speed at which these elements are moved may not necessarily be of consequence, however, the precision or tolerance and range of movement are often critical factors. For example, some optical attenuators use a variable attenuation element such as neutral density filter that is required to be moved in a controlled manner through a beam of light, attenuating the beam, by transmitting a portion of it and absorbing or blocking the remaining portion. Means are present in a variety of commercially available optical attenuators for moving an optical element through a beam of light. For example, one such product is available from JDS FITEL Inc. of Ottawa, Ontario, Canada that uses a bearing mounted lead screw and nut that moves a linear filter through a collimated beam. Although this device is very precise it is costly and somewhat bulky; as well, the device cannot be easily, mass-produced. Another similar product uses an endless belt and capstan mechanism to reduce the cost of manufacturing, however less precision and reliability are obtained. Yet another commercially available device provides a space-saving, folding cavity with only one lens for both input and output optical signals. Although this device is compact and inexpensive its accuracy, range and reliability are limiting factors.
With an ever present focus on down-sizing optical products, the demand for smaller devices and components increases.
Although the devices described heretofore may adequately perform their intended functions, it is an object of this invention to provide a more compact, less expensive device that offers suitable precision and reliability, for varying the position of an optical element in a controlled manner.